Commutator for dynamo-electric machines



(No Model.)

BTHQMSON. CCMMUTATCR FCR DYNAMC ELECTRIC MACHINES. No. 496,456.

dMay 2, 1893'. 13'

llatente l? 1| --L x| Il| all. J .H lllll -IJ l I L l|.|1 H Il- LL- 1 UNITED vSTATES PATENT OFFICE.

ELIH THOMSON, OF SWAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO THE THOMSON-HOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

v vCOMMUTATOR FOR DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 496,456, dated May 2, 1893. Application filed December 2, 1891. Serial No. 413,822. (No model.)

To all whom it may concern.-

Be it known that I, ELIHU THOMSON, a citizen of the United States, residing at Swampscott, county of Essex, State of Massachusetts, have invented a certain new and useful Improvement in Comm utators for D ynamo-Electric Machines, of which the following is a specilication.

My present invention relates to commutators and connections for dynamo electric machines, electric motors, dac., using continuous current.

One part of it relates to the introduction of a determinate amount of self-induction between the armature coils and the commutator segments, that is in the leads connecting the two, for the purpose of checking sudden rushes or reversals of current, such as accompany short-circuitin g, while the self-induction used is moderate enough in amount not to oppose to any great extent the flow of the normal current. The invention in this form is best applicable to the use of brushes such as those of carbon which are given a fixed position during the rotation, though adjustable brushes may also be used.

My invention also relates to divided leads and divided commutators whereby very large currents may be taken oft and each commutator made to take its own proper share of current, and in this form it is applicable to the case of machines for the delivery of heavy currents whether of high ,or low potential, but particularly to low potential machines.

My invention divides up the work of the commutator and reduces the current to be taken up at each commutator, thereby avoiding the diflicultiesofcommutation with large currents Where the spark is apt to be concentrated at the last point of leaving of the seg` ment from a brush and the spark becomes destructive in proportion to the volume of current which has to be controlled. It is particularly applicable to the class of machines Working with rapidly varying loads where more or less spark is inevitable, and Where 'he adjustment ot the brushes cannot be perect.

In the accompanying drawings, Figure l is a longitudinal section of a commutator embodying my improvements. Fig. 2 shows a detail. Figs. 3, 4 and 5 show modifications.

In Fig. l for convenience the commutator is shown inverted, that is the ranges of segments K K2 K3 are carried in a cylinder from which they are insulated, while the brushes bearing thereon are carried in internal brushholders H H', as shown. This construction enables the sub-leads L L2 L3 to be connected to the segments in ltheir proper relation, though the order of connection is not of much consequence and might be reversed occasionallyaround the commutator. Thus the sublead L might be connected to a segment K', while the next adjacent sub-lead, corresponding to L might be connected to the next adjacent segment in the revolution, K3, to which the sub-lead L3 is connected.

The laminated ring or mass of iron l I for obtaining the self-induction in the leads is perforated for the reception of the sub-leads, and these perforations are shown separately in Fig. 2, the leads passing through the laminations and being surrounded by the laminated iron for a certain distance. The construction enables a considerable self-induction to be introduced into the sub-leads as the thickness of the laminated mass l I may increase so as to include a considerable length of the subleads. Indeed in these constructions the leads maybe carried around a mass of iron, as indicated in Fig. 5, and may make one or more turns, as often as desirable, and this maybe done whether a system of subleads or whether simple leads are carried out to the commutator segments without subdivision.

In Fig. 3 L L represent two of a system of leads of armature coil sections on an armature. These leads L L are divided at L L2 L3, as shown, into three sets of leads which pass respectively, to segments in commutators K K2 K3, and the divided leads L L2 L3 are made to pass through a body of iron or to be adjacent to a mass of iron which would be magnetized by any considerable` current in the leads. For this purpose a mass I I consisting of a laminated ring or series of laminations through which the leads pass will generally be sufficient. 1f the current in the leads is running in a given direction theiron IOO surrounding the divided leads becomes magnetized thereby. If now the current should begin to suddenly reverse, the magnetism in the iron surrounding the leads will require to be discharged and will develop counter-induction in the lead. If one or another of the divided leads L L2 L3 tends to take an excess of current or tends to take a considerably larger current than the other, a corresponding self-induction is set up which causes the division to be more perfect and each commutator to receive that fraction of the Working current proper to it. At least these results are approximately obtainable, but never perfectly. The brushes B B B2 are, as usual, applied to the commutator at positions of proper potential and may be adjustable around it. Of course it will be understood that a circular range of segments, as usual exists, with a corresponding range of leads L L W-hich are divided into sub-leads, as indicated.

Fig. 4 indicates a construction which is applicable to the delivery of very heavy currents, such as are required for electric furnace operations or depositions. The armature A is surrounded by heavy conductors suitably placed in any Wise to give the requisite number of sections, `the Whole being mounted upon a shaft. The turns of the armature have leads extending therefrom and in this figure are shown as consisting of two leads L L each of which is divided into others L VL2 L3 L4, respectively, carried to the corresponding segments of a commutator K K2 K3 K4, the purpose and effect of which is the same as before to divide up the delivery of the current so that it shall not be too highly concentrated on any one segment of the commutator.

I claim- 1. The combination with the commutator and the armature connection therefrom of a mass of magnetic material in inductive relation to such connection.

2. The combination With the commutator, and its armature connections, of a mass of magnetic material in inductive relation to such connection.

3. The combination With the commutator, and its connections, of the laminated mass of magnetic material in inductive relation to such connections.

4. The combination with the commutator and its connections, of the mass of magnetic material having perforations through which such connections pass.

5. The combination with a single armature lead, of two or more subleads therefrom, separate insulated commutator segments connected respectively to such sub-leads, and tWo or more brushes bearing respectively on such segments.

6. The combination with a single armature lead, of two or more separate insulated commutator segments lying in the same axial plane and connected Withsaid lead.

'7. A commutator composed of two or more sets of separate insulated segments, the corresponding segments in each set lying in the same axial plane.

8. The combination with a single armature lead, of two or more sub-leads therefrom, each having a portion of largeself-induction, separate insulated commutator segment-s connected respectively to such sub-leads, and brushes bearing on such segments.

In testimony whereof I have hereunto set my hand this 28th day of November, 1891.

ELIHU THOMSON.

Witnesses:

JOHN W. GIBBONEY, BENJAMINB. HULL. 

